A clamp, basically, is an apparatus that will hold two workpieces or a workpiece and, typically, a work bench, in selected firm juxtaposition with respect to each other. One common form of the clamp is the "C-clamp", so-called because of its general resemblance to the shape of the letter "C". The typical C-clamp has a rigid curved body and a gripping surface firmly affixed to one end or arm of the C shape. The other end is movable and also has a gripping surface that can be advaced towards the first gripping surface to grip the workpiece of workpieces therebetween. In such clamps, the movable gripping surface has a limited range of movement, generally a few inches, depending on the size of the C shape. It therefore becomes necessary, in a well-equipped workshop or on a job that involves workpieces of varying sizes, to have one or more complete sets of C-clamps, e.g., ranging from those capable of gripping workpieces only a couple of inches across to large ones that may be as much as 12 or 14 inches across.
Conventional C-clamps are therefore made, sold, and generally used in sets, varying in size from the smallest to the largest. The problem with this type of C-clamp is that more than one set usually must be available for most jobs. The reason is that it is often necessary to use more than one clamp to handle an elongated workpiece. The purchase and storage of multiple sets of c-clamps therefore involves considerable expense and storage space.
Many users repeatedly deal with shaped, i.e., non-flat, items having definite profiles where the clamps must grip them. For such users, it would be particularly helpful to have clamp ends selected to suit such frequently encountered profiles, e.g., shaped to be circular, right-angled, or the like.
The need, therefore, exists for a simple, inexpensive apparatus that provides the same easy-to-use gripping function of the common C-clamp, but which can, furthermore, securely stretch to accommodate itself to workpieces of varying sizes and be readily adaptable to grip items having predetermined profiles. Thus, a single C-clamp of this invention being capable of adjusting its gripping range, would replace an entire set of conventional C-clamps.